I totally see what you are saying.
I kinda did the same as well.
I bought on Ebay for $830 incl. shipping:
Mac Pro 4.1
2 x 2.26 Ghz Quad Core
16 GB DDR3 1066 Mhz (4x4 GB)
GT120 512 MB GDDR3
250 GB 7200 RPM Samsung HDD
I have now spend a total of $1555 and my system looks like this now:
Mac Pro 5.1
2 x 2.93 Ghz Quad Core (X5570)
48 GB DDR3 1066 Mhz (4x4GB + 4x8GB)
GTX 570 2.5 GB GDDR5 + GT 120 512 MB GDDR3
Intel SSD X25M 160 GB SSD (OSX, Applications)
1 TB WD Green (Storage)
250 GB 7200 RPM Samsung HDD (Windows for Bootcamp)
CrossOver 290M 29 Inch IPS (2560x1080) Monitor
Wireless Apple Keyboard
Wireless Apple Mouse
I feel like I've got a lot of computer for a total of $1555...
Most expensive upgrades was for sure the Monitor and extra 32 GB memory...
But good luck!
Yeah I just want something reasonably inexpensive because I'm going to be in possession of 2 xeon hexacore westmere CPUs pretty soon. I figured I could just stick it in there and add ram to it and it would be ready to rock.
So far I haven't seen anything like that on eBay.